Thermofluid printing ink



Patenterloet. 31, 1944 'rnsamonum rams mx Jesse Kenne'tlrlloggs, Niagara Falls, N. Y,., and

Lotliian M. Burgess, Ohatham, N. 1., assign to J. M. Huber, Inc., New York, N. Y., a corporation of New Jersey No Drawing. Application April 24, 1941, Serial No. 390,114

. 8 Claims.

This invention relates to new and useful improvements in normally solid or thermo-fluld printing inks fo use in printing according to-the .recently developed cold set" printingprocess, as set forth, for example, in a co-pending ,ap-

plication of Walter Huber, filed August 3, 1939,

now United States Patent No. 2,268,594. In that process solid ink is heated and melted, and thenprinted in thinmolten films onto relatively cold stock so that it freezes immediately to form dry prints adhering to the surface of the stock.

Thermo-fluid ink compositions. which in other respects possess satisfactory qualities have sometimes caused trouble in use because they tended to form rough prints when printed at the required printing pressspeeds at temperatures readily available from the printing press heating system.

Whenever rough prints are produced there is a, loss of appearance and a danger of ink scraping oil and mining the paper as it passes over angle bars or folders or is otherwise subject to abrasion in the course of the printing operations. To meet this problem it has heretofore been necessary either to increase the printing temperature or to provide ink of modified composition by'ineluding inthe ink vehicle less eflective proportions or types of hardening or toughening ingredients, or more effective proportions or types of liquefying or plasticizing ingredients, so that the ink would possess a greater fluidity at the actual printing temperature and when printed would conform properly to the surface of the paper stockbefore freezing to a solid condition.

An object of this invention is to provide new thermo-fluid printing inks having improved viscosity and printing qualities at elevated printing temperatures, and, more particularly, to provide such inks which are superior to known thermoiiuid inks of comparable basic composition in that they possess similar characteristics of hardness, toughness and freedom from objectionable tack at ordinary temperatures but are much more fluid and have better printing qualities -at elevated printing-temperatures. I

Another object is to provide improved thermoiluid printing inks for high speed commercial printing operations'according to the "cold set" process. 1

stances of-high molecular weight, of which zinc resinate, zinc .naphthenate, lead naphthena-te, lecithin and Aerosol 0T (an ester of aliphatic sulfodicarboxylic acid, produced by American Cyanamid Co.) are illustrative examples. these substances contain strongly polar groups, such as metallic atoms Or sulfonic radicals, and

non-polar groups of high molecular weight, such as resinic, naphthenic, fatty acid or fatty alcohol radicals. Their use in small proportions in thermo-fluid ink vehicles of the type hereinafter described results in a pronounced improvement in the printing qualities of the'inkwhen it is melted and printed at elevated temperatures.

Our complete inks, in addition to a small'proportionof an organic polar-non-polar compound as-aforesaid, consist generally of coloring material, mainly pigments, incorporated in normally solid thermo-fiuid vehicles which melt and im-:

part the required fluidity, body, length, cohesiveness and other printing qualities to the ink at elevated printing temperatures and which freeze quickly when printed in thin ink films onto relatively cold stock so as to form substantially dry prints having the desired adherence, hardness,

smudge-resistance and freedom from tack or stickiness. The vehicles of these inks contain principally hard thermo-plastic resin and hard wax-like material, with or without minor propor- '30 tions of additional organic liquefying or plasticizing material such as certain vegetables or'minerai oils, soft resins, pitches, etc.

The hard resin content preferably includes hard cumarone resin, hard rosin or rosin deriva- 5 tive, such as the resins known commercially as Cumar and "Neville" resins-wood rosin, limed rosin, ester gum, est r gum of hydrogenated rosin, polyphenolic and li nin acid residues from wood ,rosin extraction (suchv as the product known .40 commercially as Vinsol" resin), rosin maleate ester gums and polymerized iso-butylene or bydrocarbon resins. A substantial proportion of gilsonite or, of other resin that is long" or stringy when molten, is included in the resin content of 46 some vehicles to add length to the molten ink.

In accordance with the present invention, we

have found that the trouble hereinbefore mentioned may be alleviated and that the printing qualities of various thermo-iluid inks which tend to print roughly may be substantially improved by incorporating in the ink vehicles small proportions of certain organic polannon-polar sub- The wax-like material may be a natural .wax'

such as carnauba, montan, candelilla or highmelting parafiin wax, or these natural waxes may housed in conjunction with or substituted by 60 synthetic waxes or wax substitutes, of which hydrogenated soya bean oil and monoethanolamide which possess a pronounced freedom from tack of hydrogenated castor oil fatty acids ("DB1 wax." produced by National Oil Products Co.) are preferred examples. Wax-like materials of this type,

All of and a water-like fluidity when molten, may displace oil or other soft or liquid liquefying material when used in comparatively large proportions.

In preferred embodiments of the present inventionthe thermo-fiuid vehicle is made with about 4% to 5%, by weight, of the higher molecular organic polar-non-polar compound, and the coloring pigment is ground with the vehicle in the presence of this compound to produce the final ink. The grinding operations are carried out in heated grinding mills at temperatures sufflcient to keep the fusible constituents of the vehicle in a. molten condition. In making the vehicle, the highest melting resin constituent is usually melted first in a suitably heated container, after which any lower melting resin, the

wax-like material, the polar-non-polar compound and any additional liquefying material are stirred in, in any desired order, to form a homogeneous molten mixture. ground thoroughly with the pigment, the resulting molten ink is poured into containers and allowed to cool and become solid.

' The following are illustrative examples of the improved inks:

Example 1 Parts by weight Hydrogenated rosin ester gum 5'7 Carnauba wax Blown soya bean oil -5 10 Lead naphthenate 1 Carbon black 18 Toners 4i Eramplez Ester gum #125 or American Cyanamid 00.- 62.5

As an indication of the greatly increased fluidity of the improved inks when molten, it may be mentioned that the ink of Example 4 showed a viscosity of 13 poises when tested with a Brookfield Synchro-Lectric viscoslmeter at 220 F.; whereas, another ink lacking the zinc reslnate but otherwise of the same composition showed a viscosity of 48 poises when tested at 220 F. with the same instrument. Both inks possessed hardness and' toughness characteristics desirable for thermo-fluid printing inks, but the ink of the example has printing qualities far superior to the other, particularly for high speed cold set" printing operations.

The normally solid printing inks herein disclosed are generally substantially free of volatile When this mixture has been asen'ieo setting materials or the like, so that they are substantially stableagainst chemical change .uring use, and they retain their desirable physical characteristics and printing qualities after repeated heating and cooling operations. It will be understood, however, that small proportions of such ingredients may be included in the inks for special purposes without departing from our invention.

It will also be understood that the specific constituents and formulae set forth herein are mentioned only as presently preferred examples. Our invention may be embodied in various other formulae, using the above-mentioned or various other constituents, without restriction to the details herein disclosed exceptas may be required by a fair interpretation of the appended claims.

We claim:

1. A printing ink which is solid at normal temperatures and melts to a fluid printing consistency at elevated temperatures comprising a homogeneous mixture of coloring pigment with a normally solid thermo-fluid vehicle consisting predominantly of hard, thermo-plastic resin and hard waxy material and containing from about /4% to not more than about 5% of a higher molecular organic polar-non-polar compound.

2. A printing ink which is solid at normal temperatures and melts to a fluid printing con-= sistency at elevated temperatures, comprising a homogeneous mixture of coloring pigment with a normally solid thermo-fiuid vehicle containing about 4% to 5% of a polar-non-polar ester of higher molecular sulfonated dicarboxylic acid.

3. A printing ink which is solid at normal temperatures and melts to a-fiuid printing consistency at elevated temperatures, comprising a homogeneous mixture of coloring pigment with a normally solid thermo-fluid vehicle containing about to 5% of sulfonated higher molecular aliphatic alcohol.

a. A thermo-fluid printing ink comprising solvents, oxidizing or drying ingredients, thermosolid thermo-fluid vehicle consisting predominantly of hard thermo-plastic resin and hard wax-like material and containing about 72, to 5% of a higher molecular organic polar-nonpolar compound.

5. A thermo-fluid printing ink comprising coloring pigment incorporated in a normally solid thermo-fiuid vehicle consisting of hard thermo-plastic resin as the principal ingredient, hard wax-like material, organic plasticizing material, and from about to not more than 5% of a higher molecular organic polar-non-polar compound.

6. A printing ink for the commercial printing of publications, containersand other printed matter, which is solid at normal temperatures and possessesa fluid printing consistency at elevated temperatures substantially above its meltingpoint, said ink comprising coloring pigment incorporated in a thermo-fluid solid vehicle containing predominantly hard thermo-plastic resin, hard wax, normally solid hydrogenated oil and from about 4% to about 5% of a polarnon-polar substance from the group consisting of heavy metal salts of higher molecular organic acids and sulfonated higher molecular acids and alcohols.

. 7. The method of improving the printing quality of normally solid printing ink to be printed molten condition and in the presence of a small amount of a higher molecular organic polarnon-polar compound equivalent to about to 5% of the weight of the vehicle.

thermo-fluid ink vehicle in thepresence of abouz /4% to 5%-of a higher molecular polar-nonpolar organic wetting agent, and then allowing 8. The method of improving the printing dual- 5 the ink to cool and become solid. I

ity of normally solid printing ,ink to be printed v in a heated, molten condition which comprises JESSE KENNETH BOGGS. LO'I'HIAN M. BURGESS. 

